Starting Nine: Cubs have more than a basestealing problem; Mets have more injuries

Tuesday's packed slate of games allowed for plenty of rumblings, including the Cubs' weaknesses, another key injury for the Mets and an intriguing call up out in San Francisco. Here are nine items you need to know about in baseball right now.

1. Only five games shy of the midway point in the season, the Cubs have shown they're not quite the dynamic force they were last season. There's evident holes in this year's club, two of which were severely exposed in a 6-1 defeat to the Nationals. Former Cy Young Award winner Jake Arrieta continued to get roughed up, allowing six runs (five earned) in four innings on Tuesday to balloon his ERA to 4.67. His seven starts this season allowing four or more earned runs are only one shy of the eight he had all of last year.

It became exponentially harder for Arrieta to control the damage when neither he nor catcher Miguel Montero could do anything to slow down the Nationals' running game. Washington stole a whopping seven bases in the first four innings, highlighted by Trea Turner's four swipes in the first three innings.

Underscoring the Nationals' feat was Montero's season-long issues with base stealers. He's thrown out only one baserunner in 32 steal attempts, equating to a 3% success rate. The veteran catcher's caught-stealing percentage has declined every year since peaking at 42.1% in 2012.

2. The only consistency in Alex Cobb's career has been trips to the disabled list. He's started for the Rays since 2011, yet never made more than 27 trips to the mound in one season because of a buildup of injuries that culminated two years ago with Tommy John surgery. So far this season Cobb's maintained his health, and he hadn't looked better than in the eight frames he posted Tuesday in the Rays' 4-2 win over the Pirates.

Cobb completed six masterful no-hit innings before Josh Harrison grounded one through the shifted over infield to start the seventh inning. The Tampa Bay righthander completed eight shutout innings, but didn't get a win after Alex Colome allowed two runs in the ninth to send the game to extra innings. Regardless, there's no question who Tuesday's best pitcher was.

3. In his 20th major league season, Adrian Beltre checked off one relatively big milestone within his reach Tuesday night. He clubbed a home run for the third consecutive game, this one a go-ahead shot in the ninth inning to solidify a 2-1 Rangers win over the Indians, to notch his 450th career home run. He became the third active player to reach that mark behind Albert Pujols and Miguel Cabrera.

4. The Mets’ remarkable string of injuries stretched a bit further on Tuesday in Miami. Righthander Robert Gsellman strained his left hamstring trying to beat out an infield single and is destined to become the sixth different Mets starter to hit the disabled list. Jacob deGrom would remain the only one of New York's seven primary starting pitchers to remain unscathed—for now.

Just in the last two weeks Zack Wheeler (right biceps tendinitis) and Matt Harvey (stress injury, right scapula) have been shelved. Noah Syndergaard, Seth Lugo and Steven Matz have also logged time on the disabled list this season. The Mets remain on pace to lose 90 games after falling to the Marlins, 6-3, and have little reason to think their fortunes can turn when the nucleus of their team can't stay on the field.

5. After registering a 5.60 ERA over the first two months of the season, White Sox ace Jose Quintana is gradually reclaiming his status as a top-tier trade chip. The left-hander dazzled over 6 1/3 innings against the Yankees on Tuesday night, continuing a streak of 18 consecutive scoreless frames. His ERA dipped down to 4.37—its lowest point in over a month—in Chicago's 4-3 win against the Yankees.

His success over the coming weeks will be pivotal for the rebuilding White Sox. It seems to be certain that Quintana will be moved over the next month, and rightfully or not, the return package may hinge on his performance in the next few starts. He's slated to square off with the Rangers on Sunday, a team he has a 3.38 career ERA against in 32 innings.

6. With a July 1 opt-out looming, the Giants are taking a flier on Korean third baseman Jae-gyun Hwang. San Francisco manager Bruce Bochy confirmed to reporters before Tuesday's game against Colorado that the team will purchase Hwang's contract, starting him as soon as Wednesday.

Hwang had a contract clause that would have allowed him to opt out if he was not in the major leagues by the start of July, and Andrew Baggarly of the San Jose Mercury reported that Hwang had kept in touch with KBO clubs who might be interested in poaching the Korean star back to his native league. Hwang will now begin his major league career after hitting .287 with seven home runs in 68 games with Triple-A Sacramento.